This invention relates in general to a thrust enhancer for use in a jet or rocket engine aircraft, particularly for use in lower thrust applications, such as in takeoff of missiles and light aircraft, where additional thrust from a lightweight and compact augmentation system is very desirable. The thrust enhancer is particularly suited for augmenting the thrust of engines that expel gases at near sonic or greater velocities.
Jet engines and rockets produce thrust by expelling burned gasses at high velocity. My previous U.S. Pat. No. 4,896,501 titled "TURBOJET ENGINE WITH SONIC INJECTION AFTERBURNER" describes a particular turbojet engine in which fuel is supplied to the afterburner by spraying it into several small turbine bypass ducts which connect the main combustion chamber to the forward portion of the afterburner. The hot gas and fuel mixture is expelled from the bypass ducts as sonic velocity jets because of the relative high pressure drop between the main combustion chamber and the afterburner. The sonic jets are directed into the afterburner in a tangential manner and mix with the turbine discharge.
The tangential entry of the jets creates a fuel-rich vortex stabilization mechanism in the forward portion of the afterburner duct. Flame speed is increased in this hot jet inducted vortex and combustion time is shortened. As a result, the afterburner duct can be shortened. The afterburner terminates in a restrictive nozzle such that the burnt gasses exit at near sonic or greater velocities.